- #1
Saippo
- 10
- 1
Since when you freeze liquid water, there's an expansion, wouldn't that mean there's work?
Right. In this way, work is dependent on volume. So ice does work when it's expanding. Work is simply the energy required to do something--and the ice is obviously using energy to melt. Actually, it's increasing in energy as it melts.Saippo said:delta W = pAs = pV so a change of volume would indicate a change of work wouldn't it?
Water has a lesser volume than ice.Saippo said:I guess what sort of made me wonder about it is when ice melts, the volume doesn't actually change..right? So no work. But if you freeze liquid water, ice expands. So work done?
Not only did he beat you to it, but his answer is correct, and yours isn't. Most of the energy involved in melting has nothing to do with the work done by atmospheric pressure. Also, ice receives work from the atmosphere in contracting; it doesn't expand when it melts.ProfuselyQuarky said:Right. In this way, work is dependent on volume. So ice does work when it's expanding. Work is simply the energy required to do something--and the ice is obviously using energy to melt. Actually, it's increasing in energy as it melts.
EDIT: Oh, Tazerfish beat me to it.
I wasn't talking about pressure. I was talking about volume. And I never said ice expands when it melts.Chestermiller said:Not only did he beat you to it, but his answer is correct, and yours isn't. Most of the energy involved in melting has nothing to do with the work done by atmospheric pressure. Also, ice receives work from the atmosphere in contracting; it doesn't expand when it melts.
Work is equal to ##\int{P_{ext}}dV##, where, in this case, ##P_{ext}## is atmospheric pressure. So a change in volume in melting ice is accompanied by work being done. This is a small part of the heat of melting.ProfuselyQuarky said:I wasn't talking about pressure. I was talking about volume. And I never said ice expands when it melts.
Tazerfish said:A little disclaimer: The energies in this(only for ice not other enthalpy stuff) are absolutely pathetic.
When ice melts or freezes, it undergoes a phase change from solid to liquid or liquid to solid. This involves a rearrangement of the molecules within the substance, which requires energy. This energy is known as latent heat and is responsible for the work done by ice during the phase change.
Ice does positive work when it melts. This means that it requires energy to break the bonds between the molecules and change its phase from solid to liquid. This energy is absorbed from the surroundings, causing the temperature to decrease.
Yes, ice can do work when it freezes. When liquid water freezes, it releases energy in the form of heat, which can be used to do work. This is why ice can be used to cool drinks or preserve food.
The work done by ice is related to its state of matter because it is a result of the phase change between solid and liquid. When ice melts, it absorbs energy and does positive work. When it freezes, it releases energy and does negative work. This work is necessary for the molecules to rearrange and change their state.
No, ice cannot do work without changing its state. Work is only done when there is a change in energy or motion, which occurs during a phase change. However, ice can transfer thermal energy to its surroundings without changing its state, such as when it is used to cool drinks or keep food cold.